420 SEL Overheating problem - Overheating

[Mr Wolf]

Have '93 420 SEL, vehicle runs fine with no obvious smoke / water in oil / water from ex.pipe.  On long runs at 70 - 80 mph temp stays between 80 / 90c, in traffic temp rises to 100 or just over but never ( yet ) to 120.  On hills and under load temp rises fairly quickly to 100.  If i put the ac. to hot the temp. drops quickly.  As yet it has not overheated but i am concerned at its seemingly hot running.  Is this normal? if not, any suggestions welcomed. thanks

 

[Andy]

420 SEL Overheating problem

Hi Mr W,

Theres not much wrong with your vehicle. As you have said, the vehicle should run at approx 80\90 degrees. When standing or in summer they will rise to 100 or just a tad above. If this stays like this then no problem.

For the rest of you with motors that never reach 80 and you think thats ok. Well you are wrong. The correct operating temp for ALL mercs is 80\90 degrees. If it dosn't reach that then fit a thermostat.  There will at least 50% of you running around with 190/230's all running too cold. You will find your heater will operating a lot better. Especially as we are coming to the cold season.

While were on the subject of the cold season. Don't forget to check your antifreeze strength.

Regards,
Andy @www.mercedesservicing.com

 

[prime]

420 SEL Overheating problem

Check your fan coupling if there is no friction the fan wont pull enough air through the rad.
92 1/2 W126 500 SEC had same problem

 

[Matt Crooke]

420 SEL Overheating problem

Im not sure what type of fan you have on your model, but my 190e has got a rather unusual 'Electromangnetic' cooling fan on it. After a slight overheating incedent, ive replaced the switch and its now working fine. It does say on the switch that it should activate at 100c and switch off about 85c. If youve got a standard viscous fan on the car, leave the engine ticking over until it reaches 100c or just over, you should start to see the fan spin the same speed as the engine rather than 'freewheeling', if it dosent its usually the viscous clutch not engaging.